valeri

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication43
{
    class Program
    {
        static void Main(string[] args)
        {
            var fitnesers = Console.ReadLine().Split(',').ToList();
            while(true)
            {
                string ured=Console.ReadLine();
                ured = ured.Trim();
                if(ured=="END") break;
                switch(ured)
                {

                    case ("Add visitor"):
                        {
                            fitnesers.Add(Console.ReadLine());
                            break;
                        }
                    case ("Remove first visitor"):
                        {
                            fitnesers.RemoveAt(0);
                            break;
                        }
                    case ("Remove last visitor"):
                        {
                            fitnesers.RemoveAt(fitnesers.Count-1);
                            break;
                        }
                    case ("Add visitor on position"):
                        {
                            string name = Console.ReadLine();
                            int index = int.Parse(Console.ReadLine());
                            fitnesers.Insert(index,name);
                            break;
                        }
                    case ("Remove visitor on position"):
                        {
                            fitnesers.RemoveAt(int.Parse(Console.ReadLine()));
                            break;
                        }
                }

            }

            Console.Write(fitnesers[0].Trim()+"");
            for (int i = 1; i <fitnesers.Count; i++)
            {
                fitnesers[i]=fitnesers[i].Trim();
                Console.Write(", "+fitnesers[i]);
            }
            Console.ReadLine();
        }
    }
}